Mask



FIG. 1 is a front isometric view of a mask.

FIG. 2 is a rear isometric view thereof.

FIG. 3 is a front view thereof.

FIG. 4 is a rear view thereof.

FIG. 5 is a left elevation view thereof.

FIG. 6 is a right elevation view thereof.

FIG. 7 is a top plan view thereof; and,

FIG. 8 is a bottom plan view thereof.

The broken lines illustrate portions of the mask that form no part of the claimed design. 

CLAIM I claim the ornamental design for a mask, as shown and described. 